The present invention relates to a different fuels combustion burner of the type for burning both a solid fuel and a liquid fuel simultaneously.
There have been designed and used varions types of burners for burning different kinds of fuels (to be referred to as "different fuels combustion burner" in this specification). For instance, such burners can simultaneously burn hard-to-ignite-and-hard-to-burn solid fuel particles such as anthracite, petroleum coke or the like with a liquid fuel such as heavy oil.
FIG. 1 generally shows a different fuels combustion burner. A liquid-fuel combustion nozzle 1 for injecting a liquid fuel such as heavy oil extends along the axis of the combustion burner and a solid-fuel combustion nozzle 2 with an annular nozzle opening is disposed to surround the nozzle. 1. Reference numeral 3 designates a nozzle tip of the nozzle 1; 4, a liquid-fuel supply line or pipe; 5, a nozzle tip of the nozzle 2; 6, a solid-fuel supply line or pipe; 7 and 8, air passages; 9 and 14, vanes; and 10, a furnace wall.
In the conventional different fuels combustion burner of the type described, the nozzle tips 3 and 5 are so designed and constructed as to cause a solid-fuel flame B to surround a liquid-fuel flame A as shown in FIGS. 2 and 3 so that an interference zone C where the flames A and B interfere with each other results. As a consequence, there arises the problem that "COM" phenomenon occurs.
"COM" phenomenon refers to one in which a liquid fuel and a solid fuel interfere and mix with each other so that a solid particle a is coated with a liquid fuel film b as shown in FIG. 4. When "COM" phenomenon occurs, the solid particles a tend to conglomerate into large masses. The outer liquid-fuel coating b burns first and then the hard-to burn solid particles a burn. Thus, the oxygen content in the atmosphere surrounding the combustion region of the solid particle a is lacked so that the combustibility of the solid particles a is remarkably degraded. As a result, there arises the problem that the combustion efficiency of the fuels is lower than that obtained when solid and liquid fuels are burned separately.
The present invention was made to overcome the above and other problems encountered in the conventional different fuels combustion burners and has for its object to separate liquid-fuel injection and solid-fuel injection from each other in a circumferential direction to eliminate the interference between the injected solid and liquid fuels, thereby preventing "COM" phenomenon and facilitating the ignition, whereby consumption of the liquid fuel, which is an auxiliary fuel, can be reduced while the combustion efficiency of the solid fuel can be considerably improved.